Out of 2,138 pregnant Japanese serows (Capricornis crispus), one case of the maceration of fetus was found in the winter of 1991, and examined pathologically. Because the fetus was covered with the hairs in the head and the neck regions, the fetus seemed to be implanted in the last breeding season and retained. The endometrium lacked the placentomes completely and showed metaplasia to the keratinized or non-keratinized squamous epithelium. In the non-keratinized region, the accumulation of neutrophils, eosinophils, lymphocytes, plasma cells and foreign giant cells was prominent in the subepithelial connective tissue.